Forging control

ABSTRACT

Method and apparatus for forging a workpiece in a series of press squeezes displaced along the length of the workpiece, in which the workpiece is carried by a manipulator peel which can be driven longitudinally relative to the manipulator carriage which has an intermittently operable longitudinal drive, and in which the carriage is driven towards or away from the press through the bite distance within the press cycle time, the peel is driven, during the period in which the workpiece is free of the press, relative to the carriage and in the same direction as the carriage to have a speed relative to ground higher than the carriage speed, the movement of the peel relative to ground is monitored, the drive of the peel in that direction being terminated when the peel has traversed the bite distance, and then the peel is held stationary relative to ground until the next press free period.

United States Patent 1 Harrison et al.

[ Aug. 7, 1973 FORGING CONTROL Inventors: Robert Henry Harrison,Sheffield;

John Patrick Russell, Unstone, Near Sheffield; Anthony Edward Middleton,Sheffield, all of England Davy and United Engineering Company Limited,Yorkshire, England Assignee:

Filed: Aug. 24, 1971 [21] Appl. No.: 174,363

[30] Foreign Application Priority Data Sept. 3, 1970 Great Britain42,219/70 U.S. Cl 72/8, 72/24, 72/421 Int. Cl B21b 37/12, 821d 43/02Field of Search 72/8, 11, 12, 421,

Relerences Cited UNITED STATES PATENTS 3,590,616 7/1971 Schumier 72/213,504,512 4/1970 Knowles..... 3,435,650

4/1969 Forster .3 72/24 FOREIGN PATENTS OR APPLICATIONS 1,057,026 2/1967Great Britain 72/11 57 ABSTRACT Method and apparatus for forging aworkpiece in a series of press squeezes displaced along the length ofthe workpiece, in which the workpiece is carried by a manipulator peelwhich can be driven longitudinally relative to the manipulator carriagewhich has an intermittently operable longitudinal drive, and in whichthe carriage is driven towards or away from the press through the bitedistance within the press cycle time, the peel is driven, during theperiod in which the workpiece is free of the press, relative to thecarriage and in the same direction as the carriage to have a speedrelative to ground higher than the carriage speed, the movement of thepeel relative to ground is monitored, the drive of the peel in thatdirection being terminated when the peel has traversed the bitedistance, and then the peel is held stationary relative to ground untilthe next press free period.

9 Claims, 13 Drawing Figures 1 23 I22 I D n 5 PRESS CONTROL DRIVE 78 ,16

5% it 79 H V24 M H COUNTER u PAIENIE AJQ 7 I975 3750,4135

SHEET 5 UF 8 36 i lQZLii '43 47 EIHUL' LEM H .:l XE

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INVENTOR ATTORNEY PATENIEMUB H915 3.750.436

SHEEI 6 0F 8 CARR/AGE P05 T/0N Fla .4.

RELATIVE TO CARRMGE Z1 PEEL POSITION INVENTOR .ATT ORNEY PATENIEUAUS7191s saw a or a PEEL VELOCITY CARR/AGE VELOCITY FIG. 78.

INVENTOR ATTORNEY FORGING CONTROL This invention relates to a forginginstallation comprising a forging press, a manipulator for supportingand moving a workpiece, and a control system for integrating themovements of the manipulator with the operations of the press.

A forging manipulator is a vehicle for supporting and manipulating aworkpiece during a forging operation on the workpiece. The vehiclenormally consists of a carriage, which may be rail-bound, carrying apeel which has a pair of jaws for gripping one end of the workpiece. Thepeel can be moved relative to the carriage in the longitudinaldirection, i.e., parallel to the movement of the carriage, verticallyand rotationally. The forging is effected in a series of press cycles,in each of which the workpiece is gripped and forged to the requireddimension over a part only of the length of the workpiece. After eachsqueeze, or series of squeezes, the workpiece is moved longitudinally bythe manipulator to present a different part of the workpiece to thepress. The press cycle time is the period between the initiations of theclosing movement of the press in successive press cycles. Within thisperiod, the press must close and effect the squeeze, the press opened torelease the workpiece, and the workpiece accelerated to move itlongitudinally through the required bite distance before the pressrecloses.

The manipulator is a massive vehicle and it is possible to acceleratethe manipulator and workpiece sufficiently quickly to avoid prolongingthe press cycle time, only by providing an excessively powerful drive.It has therefore been suggested to drive the manipulator carriage at aconstant speed such that it moves through the bite distance in the presscycle time; during such time as the workpiece is gripped by the press,the peel free floats, and is caused to return to a datum positionrelative to the carriage as soon as the workpiece is released. Thisrecoil of the peel may be caused by springs acting between the peel andcarriage, but it is preferable to drive the peel by hydraulic rams orthe like.

In the previous suggestion, the peel has been simply returned to a datumposition on the carriage and then moved with the carriage speed untilthe workpiece has been traversed through the bite distance. In view ofthe relatively slow carriage speed, this may involve delays incompleting the workpiece movement and cause lengthening of the presscycle time. Further, it is necessary for the operator to control themanipulator carriage speed to a value exactly equal to that required tocause the manipulator to move through the bite distance in the presscycle time, even though the latter is dependant upon the particularvalues selected for penetration and bite of the tools on the workpiece.

In the present invention, the peel is driven through the bite distanceindependently of the carriage. As the whole bite distance isaccomplished at the high peel speed, the forge free time may be reducedand the forge cycle time correspondingly lessened. The carriage maystart and finish its movement through the bite distance outside theforge free period and the carriage speed is not critical, the onlyrequirement being that the bite distance can be traversed by the peelwithin the cycle time.

Thus, a first aspect of the invention resides in a method of forging aworkpiece in a series of press squeezes displaced along the length ofthe workpiece,

in which the workpiece is carried by a manipulator peel which can bedriven longitudinally relative to the manipulator carriage which has anintermittently operable longitudinal drive, and in which the carriage isdriven towards or away from the press through the bite distance withinthe press cycle time, the peel is driven, during the period in which theworkpiece is free of the press, relative to the carriage and in the samedirection as the carriage to have a speed relative to ground higher thanthe carriage speed, the movement of the peel relative to ground ismonitored, the drive of the peel in that direction being terminated whenthe peel has traversed the bitedistance, and then the peel is heldstationary relative to ground until the next press free period.

According to a second aspect of the invention, a forging installationcomprises a forging press, a manipulator and a control system, themanipulator including a carriage, an intermittently operable drive forthe carriage, a peel carried by the carriage and a drive for moving thepeel longitudinally relative to the carriage, the control systemincluding means for measuring the movement of the carriage and means formeasuring the movement of the peel relative to the ground, and beingarranged to energise the carriage drive to drive the carriage throughthe required bite distance in each press sycle, to energise the peeldrive to drive the peel in the same direction as the carriage but at ahigher speed, through the bite distance relative to the ground duringthe period of each press cycle during which the workpiece is free of thepress, and otherwise to keep the peel substantially stationary relativeto the ground.

The invention will be more readily understood by way of example from thefollowing description of a forging installation and method of forging inaccordance therewith, reference being made to the accompanying drawings,in which FIG. 1 illustrates a forging press and manipulator,

FIGS. 2A, 2B and 2C together form a block diagram of a control systemfor controlling the press and manipulator,

FIG. 3 shows the hydraulic circuit of the'manipulator,

FIG. 4 shows the movements of the manipulator carriage and peel,

FIG. 5 shows the movement of the peel relative to the carriage,

FIGS. 6A, 6B and 6C show the variations in respectively the pressvelocity, the peel and carriage velocities, and the peel velocityrelative to the carriage,

FIGS. 7A, 7B and 7C show the variations in the carriage and peelvelocities in three different situations.

The forging installation is represented schematically in FIG. I by aforging press I2 and a manipulator 13 for supporting and manipulatingworkpieces during forging. The press 12 is shown as having a fixed base14, a fixed crosshead 15 mounted on four columns 16, and a movingcrosshead 17 which slides on the columns 16. The fixed crosshead 15carries the pressing ram 18. A fixed lower tool, or anvil, 19 issupported on the base 14, while the moving crosshead 17 carries a toptool 20. The press also has return cylinders 21 for raising thecrosshead 17. The press ram 18 and the return cylinders 21 are suppliedwith liquid from a press drive 22 under the control of the controlcircuit-23. A pulse generator 24 connected between the base 14 and thecrosshead l7 generates a pulse for each unit movement of the crossheadl7 and applies the pulses to a bidirectional counter 25, the count ofwhich is increased during movement of the crosshead 17 away from thebase 14, and decreased during the opposite crosshead movement.

The manipulator 13 consists of a carriage 30 mounted on wheels 31 whichrun on rails 32. The carriage 30 supports a peel 33 on links 33A, thepeel having jaws 34 for gripping the workpiece. The height of the peel33 can be varied by a ram 35 and its longitudinal position relative tothe carriage 30 is adjusted by a piston and cylinder unit 36. Thecarriage 30 is driven longitudinally by a hydraulic motor 37 driving apinion 38 which meshes with a rack between the rails 31. The piston unit36 is coupled with a peel position transducer 40 (FIGS. 2 and 3), whilethe hydraulic motor 37 is coupled to a carriage digitiser 41 which emitsa pulse on each unit movement of the carriage.

The control shown in FIG. 3 of the hydraulic motor 37 and the unit 36has been described in detail in application Ser. No. 132,719 whichissued as U.S. Pat. No. 3,696,651 on Oct. 10, 1972 to Robert [-1.Harrison and which has been assigned to the same assignes as the presentcase. For the present purposes, it is sufficient to state that avariable delivery pump 42 supplies the hydraulic motor 37 through adirection valve 43 and a second valve 44. The piston and cylinder unit36 has its own hydraulic power source 45, which is connnected through arecoil valve 46 and a second direction valve 47 to the cylinder onopposite sides of the piston. There are two modes of operation:

1. Valves 43, 47 are energised in the appropriate direction of movement,valve 44 is energised and valve 46 remains in the position shown. Inthis condition the two hydraulic actuators the motor 37 and the unit 36are connected in series with the pump 42 and, as a result, the peel 33,connected to the piston rod, is driven at the same speed as, but in theopposite direction to, the movement of the carriage 30, so that the peelremains stationary in space.

2. In this mode, valve 46 is actuated, while valve 44 is returned to theposition shown, valves 43, 47 remaining in the energised conditionappropriate to the direction of movement. In this case, the liquid frompump 42 does not pass to the unit 36, and the source 45 is connected inparallel with the unit 36 and the motor 37. The peel 33 is now drivenfrom the source 45 and the carriage is given an equal acceleration tocounteract the peel acceleration reaction.

The workpiece is forged along its length in a series of squeezes, beingmoved through the prescribed bite distance in the forge free periods,i.e., during those periods between successive squeezes during which theworkpiece is not gripped by the tools 19, 20. The control system shownin FIG. 2 is designed to effect this movement of the workpiece byinitiating movement of the carriage prior to the workpiece being fullyreleased by the tools 19, initiating movement of the peel as soon as theworkpiece is free of the tools and causing the peel to move at a higherspeed than the carriage speed through the bite distance, overtaking thecarriage in the process; keeping the peel stationary in space while thecarriage catches up and completes the movement through the bitedistance; and then terminating the carriage motion until the nextsequence is required for the next forge free period.

The forge control system is of a known type and includes threecomparators 50, 51, 52, to which the count of counter 25 is applied. Adatum signal representing the required stroke of the press and suppliedby device 53 is also applied to comparator 50, the output of which isapplied on line 54 to the control circuit 23 to stop the upward movementof the press. Comparator 51 has applied to it a datum signal from adevice 55 which is set to a required count, and emits a signal on line56 to control the control circuit 23 to cause slowdown of the press atthe end of the approach movement. A device 57 is set to the requiredthickness to which the workpiece is to be forged and applies acorresponding datum signal to the comparator 52. This issues a controlsignal on line 58 to stop further downward movement of the press.

The forging cycle is initiated by energising a line 60 and by operatinga forge lever or foot pedal 61. The latter applies a steady signal on aline 62 and generates a pulse on line 63. Lines 60, 62 are connected toan AND gate 64 the output of which is applied on line 65 to energise thepump 42 (FIG. 3). Line 63 is connected to an OR gate 66, the output ofwhich energises a logic circuit 67 and, through line 68, is applied tothe control circuit 23 in order to initiate the downward movement of thepress.

The press continues to descend until the comparator 51 detects equalitybetween the count in counter 25 and the value set in the device 55.Then, a pulse is applied on line 56 to change the fast lowering of thepress to the slow downward movement employed during the actual pressingoperation. When the workpiece has been pressed to the required size,comparator 52 emits a signal on line 58 which, firstly, stops thefurther downward movement of the press and starts the lifting movement.Secondly, the signal is applied on line 70 to the logic circuit 67 toenergise the hoist reset circuit 71, causing the peel 33 to be raisedand to lift the workpiece clear of the bottom tool 20. Thirdly, thesignal is applied on line 73 to a second logic circuit 74, which emits acontrol signal on line 75 to the solenoids of valves 44 and 47 (Mode 1above). As a result, the carriage 30 is caused to move away from thepress at the preselected speed, while the peel 33 is maintained fixedlongitudinally in space. Fourthly, the signal is applied on line 76 to atiming circuit 77 which, after a period of time sufficient to permit thepeel to be returned vertically to its datum position, applies a signalto a further logic circuit 78; circuit 78 then emits a signal on line 80to energise valve 46 and de-energise valve 44 (FIG. 2). Consequently,the peel 33 is accelerated away from the press at a high speed.

The required bite distance or traverse increment is set on a switch 81which applies a signal representing the bite distance in common to twoadders 82, 83. A second switch 79 is set to the over-run that will occurat the selected peel speed and applies its output to the adder 82. Whenthe forge lever or foot pedal 61 is operated, the pulse on line 63 isapplied to the logic circuit 78 to open a gate 84 and set a peeltraverse counter 85 to the sum of the values set on the switches 79, 81.

The output from the peel position transducer 40 is applied to ananalogue to pulse converter 86, the pulse output of which is applied toa serialiser 87. Similarly, the pulse output from the carriagetransducer 41 is applied through a direction sensing logic circuit 88 tothe serialiser 87, the output of which representing the movement of thepeel relative to the ground is applied to the counter 85, progressivelyto decrease the count set into it from the adder 82. The count incounter 85 is applied on line 90 to a comparator 91, to which is alsoapplied the output of switch 79. When the count in counter 85 has beenreduced by the movement of the peel relative to ground to the over-rundistance set on 79, the comparator passes a signal on line 89 to thelogic circuit 78 to terminate the signal on line 80 and de-energisesolenoid 46 and energise solenoid 44. As a result, the supply of liquidfrom the source 45 to the cylinder 36 is stopped and the peel is drivenrelative to the carriage 30 at the same speed as, but in the oppositedirection of the carriage movement, so that the peel 33 remains fixedrelative to the ground.

On the receipt of the equality signal on line 89, the logic circuit 78passes a signal to gate 84 to set again into counter 85 the sum of thebite increment and the overrun distance. As the peel overruns throughthe overrun distance, the value set into the counter is reduced to thebite increment value. Thus, in the first movement, the peel is-movedthrough a distance equal to the sum of the bite distance and overrundistance, but subsequent movements are through the bite distance only.

While this is happening, the carriage 30 is continuing to moverearwardly by virtue of the supply of liquid from pump 42 to thehydraulic motor 37, the movement being monitored by a carriagemonitoring circuit. This circuit comprises a counter 92 which receivesthe pulse output of the logic circuit 88. A further switch 93 is set tothe carriage overrun at the selected speed of movement of the carriageand applies its output on line 94 to the adder 83. On the originaloperation of the forge lever or foot pedal 61, a signal is applied online 63 to the circuit 74 to cause a gate 95 to be opened and to set inthe counter 92 a value representing the sum of the bite distance set upon switch 81 and the overrun set up on switch 93. This count isprogressively reduced during the movement of the carriage and by thepulses from the digitiser 41. The counter is compared in a comparator 97with the overrun value of switch 93 and, when equality is achieved, apulse is applied on line 98 to the logic circuit 74 to de-energise thesolenoid of valve 43. Consequently, the carriage comes to rest after itsover-run.

As in the case of the peel control circuit, the receipt of an equalitysignal on line 98 causes the logic circuit to apply a signal to opengate 95 again. Thus, in the first carriage movement, the distancetraversed is the bite distance plus the overrun distance, whilesubsequent movements are through the bite distance only.

As soon as the peel 33 has completed its movement through the bitedistance, i.e., when the comparator 91 issues a control signal to logiccircuit 78, a signal is applied by circuit 78 on line 109 to the OR GATE66. The output is applied on line 68 to initiate the next reciprocationof the press 12 and is also applied to the logic circuit 67 tode-energise the hoist reset circuit 71 so that the peel can fall asforging progresses. In this way, the press 12 continues to reciprocate,the peel being moved through the prescribed bite distance between eachreciprocation, until further movement is stopped.

FIG. 4 shows the movement of the carriage (Shown in full line) and thepeel (shown in broken line) both relative to the ground. It will beobserved that the peel starts its movement later than the start of thecarriage movement, but accelerates rapidly to overtake the carriage, andto complete the bite distance before the carriage does. The peel thenstays stationary relative to ground while the carriage catches up. FIG.5 shows the movement of the peel relative to the carriage and, again, itwill be seen that the peel first lags behind the carriage, due to theearlier start of the carriage, but then overtakes the carriage. The peelis of course sta tionary in space during the squeeze, which occurs atthe part marked A.

FIGS. 6, A, B and C show on the same time scale (A) the speed of thepress, (B) the peel and carriage velocities, the peel velocity beingshown in broken line, and (C) the speed of the peel relative to thecarriage. On FIG. 6A, the timing of various switching signals areindicated. These are A: the signal on line 68 causing fast downwardmovement of the press B: the signal on line 56 causing press slowdown C:signal on line 58 causing stopping of downward movement of the press andreturn D: application of a signal to circuit 71 de-energising the hoistreset.

E: signal on line 75, initiating carriage traverse F: signal on line 80initiating recoil of peel 33 G: signal on line 54, terminating returnmovement of the press I-I: signal from comparator 91 to logic circuit 78terminating the signal on line 80 and stopping peel traverse J: signalon line 98 terminating the signal on line the stopping carriagetraverse. The suffices applied to the letters in FIG. 5A refer to thenumber of the forging cycle. It will be observed that signals A2, B2,i.e., the signals on lines 68 and 56 during the second cycle, appearbefore J1, the signal terminating the carriage movement of the firstcycle. Clearly, the relative timings of A2, B2 and J1 depend on the sizeof the bite and the speed of the carriage and FIGS. 7A, B and C showdifferent possibilities. In each, the carriage velocity is shown in fullline and the peel velocity in dotted line.

FIG. 7A corresponds to the situation of FIG. 6B where the bite distanceis sufficiently small for the carriage to move through that distance ina period not much exceeding the forge free period; consequently, thecarriage is allowed to come to rest before reaccelerating for the nextforge cycle. As the bite distance increases (with no change in thecarriage velocity), the carriage has less time to come to rest at theend of one movement before starting the movement for the next cycle. Forexample, as shown in FIG. 7B, the carriage traverse is de-energised atthe timing point J1, but is reenergised at E2 only a short timethereafter, so that the carriage velocity does not in fact reach zero.In FIG. 7C the bite distance has been so far increased that E2, theenergising of the carriage traverse, now occurs before J1, thede-energising of the carriage traverse for the previous cycle.Therefore, the velocity of the carriage remains constant and thecarriage moves continuously at constant velocity. The situation of FIG.7C represents the greatest bite distance for the circuit illustrated. Ifa larger bite distance is required, it will be necessary to delay theapplication of signal on line 68 initiating the next forge cycle, untilthe carriage has moved through the bite distance.

We claim:

1. A method of forging a workpiece in a series of press squeezesdisplaced along the length of the work- 7 piece by employing a forgingpress and a manipulator comprising a carriage which is movable towardsor away from said press an intermittently operable drive for saidcarriage,

a peel which is mounted on said carriage for move ment relative theretoand which carries said workpiece, and

means for driving said peel relative to said carriage,

the method comprising the steps of a. monitoring the movement of saidcarriage b. de'energising said drive each time said carriage has movedthrough the bite distance c. while said workpiece is held by said press,operating said peel driving means to drive said peel relative to thecarriage in the direction opposite to the carriage movement and therebyto hold said peel stationary relative to the ground d. on release ofsaid workpiece by said press, operating said peel driving means to drivesaid peel in the same direction as said carriage at a speed relative toground higher than the carriage speed c. monitoring the movement of saidpeel relative to ground f. terminating the operation of said peeldriving means when said peel has traversed the bite distance, and

g. thereafter, if said carriage is still moving, energising said peeldriving means to drive said peel in the direction opposite to thecarriage movement to maintain said peel stationary to the ground.

2. A forging method according to claim 1 in which the carriage drive isenergised each time the separation of the press tools is initiated.

3. A forging method according to claim 1 in which the movement of thepeel relative to the ground is monitored by monitoring the movement ofthe peel relative to the carriage and comparing the movement of thecarriage relative to the ground.

4. A forging method according to claim 1 in which the completion ofmovement of the peel through the bite distance initiates the next of thepress.

5. A forging installation comprising a. a forging press operable toperform a series of press operations on a workpiece, each operationbeing performed in a press cycle time,

b. a manipulator having a carriage movable towards or away from saidpress, an intermittently operable drive for said carriage, a peelmounted on said carriage for longitudinal movement relative thereto andadapted to support a workpiece and peel driving means for driving saidpeel relative to said carriage in either direction, and

c. a control system including d. means for measuring the movement ofsaid carriage,

e. means for measuring the movement of said peel relative to the ground,

f. means controlled by said carriage measuring means for operating saidcarriage drive to drive said carriage through the bite distance duringeach press cycle time and to deenergise said drive means on completionof the bite distance movement,

g. means for energising said peel driving means to drive said peel atthe same speed as, but in the opposite direction to, the movement ofsaid carriage while said workpiece is held by said press,

h. means controlled by said peel measuring means for operating said peeldriving means to drive said peel in the same direction as, but at ahigher speed than, said carriage on release of said workpiece by saidpress, and for terminating the peel movement when said peel hastraversed said bite distance,

. means operated when said peel has traversed said bite distance forthereafter operating said peel driving means to drive said peel at thesame speed as, but in the opposite direction to, the carriage.

6. A forging installation according to claim 5 in which the means formeasuring the peel movement relative to the ground comprises means fordetecting the peel movement relative to the carriage and the carriagemovement relative to the ground, and means for combining the outputs.

7. A forging installation according to claim 5 in which the controlsystem is so arranged as to initiate the carriage drive prior to theinitiation of the peel movement in the same direction.

8. A forging installation according to claim 7 in which the controlsystem includes means for generating a control signal to reverse thepress when the workpiece has been forged to the required dimension, andthat control signal is applied to initiate carriage movement.

9. A forging installation according to claim 5 in which the means formeasuring the movement of the peel relative to ground generates a signalwhen the peel has moved through the bite distance, and that signal isapplied to stop further movement of the peel in that direction and toinitiate the next forge cycle.

* i U l

1. A method of forging a workpiece in a series of press squeezesdisplaced along the length of the workpiece by employing a forging pressand a manipulator comprising a carriage which is movable towards or awayfrom said press an intermittently operable drive for said carriage, apeel which is mounted on said carriage for movement relative thereto andwhich carries said workpiece, and means for driving said peel relativeto said carriage, the method comprising the steps of a. monitoring themovement of said carriage b. de-energising said drive each time saidcarriage has moved through the bite distance c. while said workpiece isheld by said press, operating said peel driving means to drive said peelrelative to the carriage in the direction opposite to the carriagemovement and thereby to hold said peel stationary relative to the groundd. on release of said workpiece by said press, operating said peeldriving means to drive said peel in the same direction as said carriageat a speed relative to ground higher than the carriage speed e.monitoring the movement of said peel relative to ground f. terminatingthe operation of said peel driving means when said peel has traversedthe bite distance, and g. thereafter, if said carriage is still moving,energising said peel driving means to drive said peel in the directionopposite to the carriage movement to maintain said peel stationary tothe ground.
 2. A forging method according to claim 1 in which thecarriage drive is energised each time the separation of the press toolsis initiated.
 3. A forging method according to claim 1 in which themovement of the peel relative to the ground is monitored by monitoringthe movement of the peel relative to the carriage and comparing themovement of the carriage relative to the ground.
 4. A forging methodaccording to claim 1 in which the completion of movement of the peelthrough the bite distance initiates the next of the press.
 5. A forginginstallation comprising a. a forging press operable to perform a seriesof press operations on a workpiece, each operation being performed in apress cycle time, b. a manipulator having a carriage movable towards oraway from said press, an intermittently operable drive for saidcarriage, a peel mounted on said carriage for longitudinal movementrelative thereto and adapted to support a workpiece and peel drivingmeans for driving said peel relative to said carriage in eitherdirection, and c. a control system including d. means for measuring themovement of said carriage, e. means for measuring the movement of saidpeel relative to the ground, f. means controlled by said carriagemeasuring means for operating said carriage drive to drive said carriagethrough the bite distance during each press cycle time and to deenergisesaid drive means on completion of the bite distance movement, g. meansfor energising said peel driving means to drive said peel at the samespeed as, but in the opposite direction to, the movement of saidcarriage while said workpiece is held by said press, h. means controlledby said peel measuring means for operating said peel driving means todrive said peel in the same direction as, but at a higher speed than,said carriage on release of said workpiece by said press, and forterminating the peel movement when said peel has traversed said bitedistance, i. means operated when said peel has traversed said bitedistance for thereafter operating said peel driving means to drive saidpeel at the same speed as, but in the opposite direction to, thecarriage.
 6. A forging installation according to claim 5 in which themeans for measuring the peel movement relative to the ground comprisesmeans for detecting the peel movement relative to the carriage and thecarriage movement relative to the ground, and means for combining theoutputs.
 7. A forging installation according to claim 5 in which thecontrol system is so arranged as to initiate the carriage drive prior tothe initiation of the peel movement in the same direction.
 8. A forginginstallation according to claim 7 in which the control system includesmeans for generating a control signal to reverse the press when theworkpiece has been forged to the required dimension, and that controlsignal is applied to initiate carriage movement.
 9. A forginginstallation according to claim 5 in which the means for measuring themovement of the peel relative to ground generates a signal when the peelhas moved through the bite distance, and that signal is applied to stopfurther movement of the peel in that direction and to initiate the nextforge cycle.